A volute of a centrifugal pump includes a proximate section. The proximate section includes: an outer peripheral portion having a tapered shape such that, within a range of a rotational trajectory of each of vanes provided on an impeller, the outer peripheral portion gradually spreads out in a direction axially away from the vane; and an inner peripheral portion having a tapered shape such that, within the range of the rotational trajectory of each of the vanes, the inner peripheral portion tapers in the direction axially away from the vane. The inner and outer peripheral portions are spaced apart from each other with a flat proximal opposed surface portion therebetween. The opposed surface portion is opposed to respective axial end surfaces of vanes of the impeller. The volute also includes a peripheral wall surrounding the peripheral surfaces of the vanes.

A volute of a centrifugal pump includes a proximate section. The proximate section includes: an outer peripheral portion having a tapered shape such that, within a range of a rotational trajectory of each of vanes provided on an impeller, the outer peripheral portion gradually spreads out in a direction axially away from the vane; and an inner peripheral portion having a tapered shape such that, within the range of the rotational trajectory of each of the vanes, the inner peripheral portion tapers in the direction axially away from the vane. The inner and outer peripheral portions are spaced apart from each other with a flat proximal opposed surface portion therebetween. The opposed surface portion is opposed to respective axial end surfaces of vanes of the impeller. The volute also includes a peripheral wall surrounding the peripheral surfaces of the vanes.

A pump with high performance and cleanability includes a casing having a smaller volute and a larger volute; a space between an outer circumference of an impeller and a starting end of the smaller volute being greater than that of the larger volute, generating a circulating flow of self-priming water from the smaller volute to the larger volute; and a diffusing part of the larger volute being formed into an upright, cylindrical self-priming water separating chamber guiding the self-priming water from the smaller volute to flow in for air-water separation. An inner circumference part of the casing is formed concentric with the outer circumference of the impeller with a predetermined space therebetween; defining members are protrusively disposed on the inner circumference part of the casing so as to define the shapes of the two volutes; and the self-priming water separating chamber is made attachable to and detachable from the casing.

A pump with high performance and cleanability includes a casing having a smaller volute and a larger volute; a space between an outer circumference of an impeller and a starting end of the smaller volute being greater than that of the larger volute, generating a circulating flow of self-priming water from the smaller volute to the larger volute; and a diffusing part of the larger volute being formed into an upright, cylindrical self-priming water separating chamber guiding the self-priming water from the smaller volute to flow in for air-water separation. An inner circumference part of the casing is formed concentric with the outer circumference of the impeller with a predetermined space therebetween; defining members are protrusively disposed on the inner circumference part of the casing so as to define the shapes of the two volutes; and the self-priming water separating chamber is made attachable to and detachable from the casing.

A centrifugal pump device has at least one impeller (16), a circulation connection between a delivery side (22) of the at least one impeller (16) and a suction side (20) of the at least one impeller (16), and a valve arrangement (30, 46) in said circulation connection (44, 54). The valve arrangement (30, 46) has a first valve mode providing a pressure dependent shut-off valve (46) in the circulation connection. The valve arrangement (30, 46) allows a change between the first valve mode and at least one further valve mode. The at least one further valve mode provides at least one fixed closing degree of the circulation connection (44, 54).

A centrifugal pump to improve the efficiency of fluid flow, and minimize long term wear on the pump by progressively increasing fluid pressure as fluid moves from an eye of an impeller towards diffuser blades, into the volute and out through an outlet that is medio-laterally aligned with an inlet. The fluid pressure is increased by progressively increasing the volume through which the fluid travels. A tear-drop shaped volute casing surrounding the diffuser and impeller creates a pocket of maximum pressure just below the outlet. A dampener dampens the vibration of the motor. A cylindrical basket strainer is provided with a flat face abutting against the volute casing to distribute pressure evenly. A clamp ring is provided to easily seal and access the basket strainer using a plain rod.

The application discloses a multipurpose transfer pump free of secondary water filling, which comprises a cover plate, a water filling plug, a pump body, an impeller, a pump body flange and a motor, the pump body flange is provided at an end portion of the motor, the pump body is provided on a front surface of the pump body flange, a volute chamber corresponding to the impeller is provided in a back surface of the pump body in an inwards recessed manner. In this way, the multipurpose transfer pump free of secondary water filling disclosed by the application can achieve a self-priming effect without filling water into the pump body when the motor works for a second time, thus improving the impeller lubricating effect.

A quick no-water startup apparatus for a centrifugal pump includes, from top to bottom in sequence, one-way passages (1), a self-priming chamber housing (41), sliding devices (5), a self-priming chamber (4), chamber partition plates (2) a concave-convex impeller (3), inlet channels (6) connected on two sides of the self-priming chamber (4), a spring device (7) of an upper-side x-shaped gas-liquid separation device, the upper-side x-shaped gas-liquid separation device (8), upper and middle-side gas-liquid separation device connecting shafts (9), a middle-side gas-liquid separation device (10), lower-side backflow-type gas-liquid separation devices (11), v-shaped backflow channels (122), an inverted v-shaped inlet channel (121), and an inlet. The quick no-water startup apparatus of the present invention enables the centrifugal pump to directly enter a normal operating condition after no-water startup, and 36 times of air exhaust can be completed while the concave-convex impeller (3) in the self-priming chamber (4) rotates by a circle in the early stage. Besides, the apparatus is provided with the upper, middle, and lower gas-liquid separation devices to fully realize separation of gas and liquid, so that gas can be exhausted more quickly and the chamber is filled with water. Therefore, the working efficiency is significantly improved and the operation process is greatly simplified.

A quick no-water startup apparatus for a centrifugal pump includes, from top to bottom in sequence, one-way passages (1), a self-priming chamber housing (41), sliding devices (5), a self-priming chamber (4), chamber partition plates (2) a concave-convex impeller (3), inlet channels (6) connected on two sides of the self-priming chamber (4), a spring device (7) of an upper-side x-shaped gas-liquid separation device, the upper-side x-shaped gas-liquid separation device (8), upper and middle-side gas-liquid separation device connecting shafts (9), a middle-side gas-liquid separation device (10), lower-side backflow-type gas-liquid separation devices (11), v-shaped backflow channels (122), an inverted v-shaped inlet channel (121), and an inlet. The quick no-water startup apparatus of the present invention enables the centrifugal pump to directly enter a normal operating condition after no-water startup, and 36 times of air exhaust can be completed while the concave-convex impeller (3) in the self-priming chamber (4) rotates by a circle in the early stage. Besides, the apparatus is provided with the upper, middle, and lower gas-liquid separation devices to fully realize separation of gas and liquid, so that gas can be exhausted more quickly and the chamber is filled with water. Therefore, the working efficiency is significantly improved and the operation process is greatly simplified.

A self-priming starting device for a centrifugal pump is mounted on a water inlet pipe of the centrifugal pump and includes an outer housing, an inner housing, a primary spacer, a secondary spacer, an opening and closing disc and a tertiary spacer which are sequentially provided in the outer housing from top to bottom, and an elastic steel plate provided in the water inlet pipe. A drum is provided in the inner housing, and air inlet pipes and air discharging pipes are provided on the inner housing. The drum is provided with drum chambers and a three-blade support is provided in the drum. The opening and closing disc is provided with a vertical rod. A gas-liquid cutter is provided between the primary spacer and the secondary spacer. The primary spacer, the secondary spacer, the opening and closing disc and the tertiary spacer are provided with through-holes.